DC-to-DC converters are used to convert an input DC voltage to a different output DC voltage for delivery to a load. Such converters typically comprise a transformer that is electrically coupled via a switching circuit between the voltage source and the load. Converters known as single-ended forward converters are a class of converters that rely on a single switch connected between the voltage source and the primary winding of the transformer to provide forward power transfer to the secondary winding of the transformer when the switch is on and conducting.
To discharge the leakage inductance at the transformer, the transformer core is "reset" during the off period of the switch. Resetting is typically accomplished with the use of additional circuitry, such as a third transformer winding in parallel with the primary transformer winding, or a LC resonant circuit electrically coupled to the secondary winding. The driving waveforms of such circuitry, however, exhibit a "dead time", a period during which the switch remains open, the voltage across the switch equals the source voltage, and the current vanishes. Dead time decreases the overall efficiency of the converter and places voltage stresses on the switch.
It is an object of the present invention to provide a single-ended forward DC-to-DC converter that effectively resets the transformer core while exhibiting substantially no dead time and minimizing voltage stress on the components thereof.